Linearization of a radio frequency (RF) power amplifier is an important design technique to achieve a high linearity of an RF power amplifier. The term “linearity” refers to the ability of the amplifier to produce signals that are accurate copies of the input but at increased power levels. In an ideal RF power amplifier, a transfer function that describes the relationship of input power to output power is linear. In actual RF power amplifiers, the transfer function is a non-linear function. Typically, as the input power increases, the amplifier has more and more difficulty maintaining the same level of amplification, that is, the gain begins to drop. When the output of the amplifier differs from the input, this difference introduces distortion into the output. For example, when the output of an RF power amplifier is clipped, this introduces high-frequency components into the output signal that were not present in the input signal. Thus, in real (not simulated or ideal) RF power amplifiers, the gain is a non-linear function that varies with input signal level.
To address the issue of gain being a non-linear function that varies with input signal level, an RF frequency power amplifier is generally made up of amplifier stages that are each configured to provide portions of a total gain. Due to ever-increasing spacing requirements, it is advantageous to fabricate the plurality of amplifier stages on a monolithic integrated circuit using gallium nitride (GaN) technology. However, heretofore maximizing both linearity and efficiency of a plurality of amplifier stages on a monolithic integrated circuit using GaN technology has been unrealized. Thus, a need remains for a GaN power amplifier that has a plurality of amplifier stages fabricated into a monolithic integrated circuit that maximizes both linearity and efficiency.